Note: Descriptions are shown in the official language in which they were submitted.
11)4~
This inventio~ relaites to an appairatus which may
take the form of a stairway or pair of steps, the treads
of which ~re always automatically maintained parallel to the
ground regardless of the angle of the stringers relative to
the ground. In consequence, when the apparatus is brought
into a horizontal position, the treads form a substantially
continuous plate.
Apparatus is already known which includes treads
which are maintained horizontal regardless of the angle of the
apparatus, such apparatus being used particularly for gangways
connecting harbour quays with floating bridges or launches
which are at a lower level than the quays but which are
vertically movable with the rising and falling tide. With
such apparatus it is not necessary for the treads to form a
continuous plate intended for receiving a large load, and for
the load to be distributed over substantially the entire length
of the two stringers so that one stringer shall rest upon the
other. ~;
- Ladders are also known, in which the stringers are
pivotally mounted relative to a lower tread and a fixed,
- horizontal upper tread, as are ladders comprising a pair of
fixed stringers, relative to which another pair is capable
of being spxead out or folded in.
'
' '
'
~ n object of this inventiQn is to provide s~ch
appara~us which is perfectly stable when resting upon the ends
- 2 - ~
:1~14~
of the strin~e~s and, whell b1ought to the horizontal, forms
a continuous and solid plate.
A further object or the invention is to provide
such apparatus in which each o~ the treads constituting
the plate is supported by each of the stringers, the angle
of the staircase being variable and not in any way leading
to variations in absolute horizontality of the treads.
Accordingly, the invention provides apparatus for
use as stairs, steps and the like, comprising a first, lower
pair of parallel, rectilinear stringers, a second, upper
pair of parallel,rectilinear stringers; each stringer in
the lower pair being disposed belo~ and parallel to a
respective stringer in the upper pair; a pair of horizontal,
parallel arms between which first ends of the stringers are
disposed, said first ends o~ the stringers being articulated
to said arms about pivot axes extending between the arms:
the said pivot axis for the lower stringers being offset
downwards by a predetermined vertical distance from that
. .
axis pertaining to the upper stringers: a plurality o~ treads
disposed between the stringers; each tread being pivoted to the
lower stringers about a first axis and to the upper stringers
about a second axis: the pivot a~es associated with each
stringer being spaced apart longitudinally of the stringer
by a distance comparable to the width~ of the treads~each
of said treads beiny provided with at least one downwardly
~xtending member adjacent one edge by way of which member
the means o~ articulation between the tread and each lower
~ 3 -
.
.: . .. . , : ...................................... . .
: - ~
` stringer is supported, whereby the fixst and second axes
of each tread are offset vertically by a distance equal
to the sum of the distances, f irst~ between the upp~r
longitudinal edges of the lower stringers and the pivot
axis of those stringers relative to the arms, and secondly
between the lower longi~udinalédges of the upper stringers
and the pivot axis of those stringers relative to.the arms,
whereby, when the stringers are pivoted relative to the arms
the treads remain horizontal and the lower longitudinal
edge of each upper stringer rests upon the upper longitudinal
edge of the respective lower stringer when the stringers are
disposed horizontally..
In ~he practical embodiment to be described herein,
the spacing between the p.ivot axes along the stringers is
slightly greater than the widths of the treads.
The p.iVotal connection of the tread and stringers
in
can be achieved/two preferred ways; either by the use of two
tubesintegrally attached to each txead and slid onto bars fixed ~ -
between the stringers, the treads carrying perpendicular,
underlying, longitudinal flanges bearing agai.nst the tubes: :~
or alternatively by the provi.sion on the treads of perpendicular
lateral flanges, through which there pass rods fixed to each
stringer.
- The apparatus may alternative~ b~ arranged so that
it may be used as a pair of steps, from which condition it
- may b~ colla~ed to form a wheeled structur~ suitable for
use as a truck,trolley or barrow~
.
. . . ~,
Tll~ invelltion will now be desc~ibed by way
of example with reference to the drawings in which:~
Figure 1 is a diagxammatic side view o~ appaxatus
embodying tha invention in an inclined position;
Figure 2 is a view in the same direction as Figure
1, but showing the apparatus in the horizontal position: -
Figure 3 is a partial longitudinal section through
the apparatus showing a first arrangement for fixing a tread
tothe stringers:
Figure 4 is a view to an enlarged scale, looXing
from the left of Figure 3;
Figure S is a view similar to Figure 3 showing a
second arrangement for fixing a tread to the stringers:
Figure 6 is a view similar to ~igure 4 but showing
the parts in Figure S;
Figure 7 is a perspective view looking from the side
of a second embodiment o~ apparatus in the form of a pair
of steps, in an erected condition;
Figure 8 is a view to an enlarged scale showing the
` embodiment of Figure 7 in a collapsed condition in which the
; . apparatus forms a hand truck;
Figure 9 is a side view of latching mechanism of
the embodiment shown in Figures 7 and 8 in the position
occupied by the mechanism when the apparatus is in its
. collapsed condition;
- Figure 10 shows the mechanism of Yigure 9 in the
' - S -
,, ., ; . " - .-.- ,. . . . . . . ..... . ...... . . ...... . .
. ;.. ., , .,, .. . : .. . . ; . ~ . . .
... ~.. ...... ,.. , .. ., . ~ . .
4 ~
position it occu~i~s wh~n the appar~tus is in a position
intermediate its collapsed and erected conditions; and
Figure 11 shows the mechanism in the position
corresponding to the erected condition of the apparatus.
Referring to Figures 1 and 2, apparatus in
accordance with a first embodiment ~f the invention may
be made to occupy either an inclined position (Figure 1)
in which it serves as a flight of stairs, or a horizontal ~ .
position in which it serves as a gangplanX, or the like. -:
~n the inclined position a series of treads 8 are in vertically
spaced arrangement, whereas in the horizontal position the -
treads are juxtaposed or are separated by small gaps.
In these igures, the main parts of the apparatus
have been depicted diagrammatically. Essentially the
apparatus comprises a main frame consisting of a pair of .~ .
spaced apart lower stringers 1, a paix o spaced apart upper
stringers 2 and a pair of spaced apart support members or -
arms 3, to each of which one stringer 1 and one stringer 2 are
pivoted for movement about respective axe~ 4 and 5. Only one ~ :
of each of the parts 1 to 3 is visible in Figures land 2, the
other ones of these parts being obscured from view.
The treads 8 occup~ positions between the two .~
pairs of stringers, each tread being articulated to the lower .
stringexs about the pivot axes 6 and to the upper stringers
about pivot axes 7. Each tread is piYoted tc the lower
stringers by way of blocks or spacers 9.
A fixed trcad 10 is depicted as being provided
- 6 - ~ :
. . r
', , '; ' ~ , .. . . ' ' ' ' !, , , ' . .. , ` .' ~:
1~ 9
~i between the arms 3 but this tread may be omitted in suitable
circumstances.
The axes of rotation 4 and S lie in respective
horizontal planes spaced by/predetermined vertical distance
equal to the ~istance between horizontal planes in which lie
the axes 6 and 7 of each ~read 8. ~his spacing is also equal
to the width of each of the stringers 1 or 2 in the case
where these stringers are iden~ical and where the centres
of the pivot axes 6 and 7 lie on the median longitudinal
lines of the stringers 1 and 2, respectively. This spacing
is also equal to the height of the block or spacer 9.
Figures 3 and 4, show one arrangement for mounting
the treads 8 between the stringers, in which the axes of
articulation 6 and 7 are provided by rods 10 which extend
13
between the stringers and are held in place by nutæ/screwed
onto the ends of the rods and bearing against the stringers
through washers 14. Each rod carries a tube 11 held ~ast with
the associated tread by flanges 12 embracing the tube. The
flanges 12 associated with the upper stringers depend directly
from the tread. The other flanges are formed on a spacer or
blocX 9 to o~fset these flanges in a vertical sense by the
desired distance.
Referring now to Figure~ 5 and 6, a second
ar~angement ~or mounting the treads 8 to pivot about axes
6 and 7, is achieved by orming or providing each tread with
;
a depending flange or wall 16 at each end. Rods 15 located
; , - 7 ~
.. .
,
~ Q4~
in appropriate positions having regard to the amount of
offset to be obtained extend between the respective stringers
and through the walls 16. The ends of the rods are made rigid
with the outer sides of the stringers, conveniently by
upsetting using a rivetting tool for aesthetic reasons~
The ends of the rods are thinned down so that only the part 17
passes through the stringers and there is obtained a double
blocking of the stringers 1 and 2 on the rods 15.
A washer 18 prevents frictional contact of the walls
16 with the stringers 1 and 12. These walls 16, as can best
~e seen in Figure 5, are o~ a sufficient height to permit the
pivot axis 6 (i.e. the iaxis of the rod 15 of the stringer 1)
to be offset relative to the pivot iaxis 7 (i.e. the iIXis of the
rod 15 of the other stringer 2).
Referring now to Figures 7 and 8, apparatus in accordance
with the second embodiment is o~ basically the same construction
as the first embodiment and has an erected condition ~Figure 7)
in which it serves as a pair of steps and a collapsed condition
~Figure 8) in which the apparatus may be transported on its
wheels, being used if desired as a handtruck or barrow. The
treads of this embodiment are shown to be of the type
illustrated in ~igures S and 6 but of course those shown
in Figures 3 and 4 may be used in their place.
In order to hold the apparatus in the erected
condition it is equipped with support members ormed of two
- 8 -
~ 9
-- bars 19, 20 of flat or pro~iled section articulated be~ween
the horizontal arms. The pivotaxis 21 o~ the support
elements does not intersect the m~dian line of these members
19 and 20, but is off-set f~om these membe~ to such an
extent that they are provided with posts 22 ~Figures 9, 10,11)
which carry the pivot rod so that the suppo~ members 19,20
can swing from a position below the horizontal arms 3 ~Figure 7)
to a rest position, above the horizontal arms 3 ~Fi~ re 8).
Between the support members 19, 20, which will act
as guide arms for the carriage, here are mounted a cross-
bracing 23 and a transverse member 24 perpendicularly to
the support members 19 and 20. The transverse me~er 24 may
be a tube which serves for pushing or pulling the apparatus
when in its collapsed, truck-forming condition.
In this collapsed condition ~ixed wheels 25 mounted
in brackets fixed upon the lower stringers 1, and steering
wheels 26 mounted (not shown) in known manner below the fixed
tread 10 make contact with the ground.
When the apparatus is erected, i.e. set in its
step-ladder forming condition, it is necessary to ensure that
the stringers and support members maintain a given angle of
separation. To this end, a latching system is provided which
can take any suitable form but which is pre~erably as shown
in Figures 9 to 11, where there are provided four latching
or blocking points, which are encircled at 27 (Figure 9),
28, 29, 30 (~igures 11).
As shown in these ~igures, a top step unit is ~ormed
_ 9 -
, ~ , . , ~ ,
.~
" : :
:, . . :
1~44~
by the horizontal arms 3 which are interconnected by a
cross-memb~r formed from a hollow section, within which
are mounted spindles 4, 5 on whi h the stringers 1 and 2
are supported, and also a spindle 21 for support member~ l9
or 20. Parts of the hollow section are cut away 60 as to permit
movement o~ the stringers l and support members 19 and 20
during erecting and collapsing o the apparatus. The parts
of the hollow section which remain after these pieces have
been cut away are upper and lower horizontal parts 31 and 32
respectively, the foxmer beiny wider than the latter.
In the collapsed or carriage forming position (~igure 9)
each lower stringer 1 is held to thc pertaining upper stringer
2 by a latch 33 having a notch 34 in which is recei~ed a stop
35 projecting from the side of the stringer. It is not
essential for this latching point (denoted by circle 27) to be
provided but it has the advantage of preventing lifting of the
opposite end o~ the top step unit when a heavy pressure is
applied to the other end of said unit by the support members
19, 20, paxticularly when the apparatus is used as a trolley
or barrow and more especially when it is no~ loaded.
When the support members 19, 20 are swung up in
the direction of arrow 36 (Fi~ure 9), they may be used as ,~!,
guide arms ~or the trolley formed by the apparatus. By
releasing the latch 33 and continuing the rotational movement
of the support membexs l9, 20 in the direction o~ arrow 37,
a roller 38 which interconnects the ends of the support members
will come to bear a~ainst the lower stringers l and tend to
1()
iO~69
raise ~hem into an upright position ~Figure 6). This
movement also xesults in the upper s~ringer being raised, - -
and at ~he same time the top step unit i~cluding arms 3 is
lifted. By still continuing to rotate the support members
19 and 20 in the direction of arrow 39, the position shown
in Figure 11 is reached, in which the roller 38 bears againqt
the underside of the horizontal part 31 of the top step unit
(as encircled at 29) as do the ends 40 of the lower stringers
1 (as encircled at 29) and the ends 41 of the upper stringers
~as encircled at 30). As soon as this position is reached,
further rotation is preventéd so that a position cannot be
reached in which there is a smaller angle between the
stringers and support members. To prevent re-opening of the ~-
apparatus, there is provided, preferably on each side, a -
latching arm 42 which is fixed to the side of a respective
one of the underlying stringers 1. The arm 42 has a notch
43 which fits over a stop 44 projecting from the internal
face of a respective support member 19 or 20, so as to
constitute a further latching point (encircled at 28, Figure 11).
.
In order that the above described blocXing and
latching actions shall be automatic, the end 45 of the latch
33 i8 chamfered and the latc~ is hinged to pivot freely about ~ -`
the spindle 4. When the steps are being returned to the
collapsed position, the end 45 will slide upon the stop 35 when
a predetermined position has been reached ~Fi~ure 10), so that
later in the collapsed position ~Figure 9) the notch 34 will
lie opposite the stop 35 80 that the latch falls over the stop,
unblocking being carried out automatically a~ indicated
above.
Similarly, the notch 43 is arranged to automatically
receive the stop 44. To ensure this, the blocking arm 42,
which pivots freely about a spindle 6 o the lower stringer 1,
extends beyond this spindle as far as the spindle 7 of the
upper stringer 2, so that its end 46 abuts this spindle 7
(Figures 9 and 10) and so that the blocking arm 42 cannot
fall into the verti~al position but, on the contrary, will
be maintained approximately horizontal, so that the chamfered
end 47 of this arm,once/predetermined angle between the parts
has been reached (exceeding that shown in Figure 10) will
abut against the ætop 44 and finally the notch 43 will fall
onto the stop 44.
Unblocking will not however be automatic but will
be caused by raising the blocking arm or arms 42.
As can be seen in Figure 11, the ends 40 and 41
of the stringers 1 and 2 are also cut to a ~hamfer, to an
angle determined so~that they abut solidly against the internal
face of the croiss-member 71 of the top step unit. ~evertheless,
to permit rotation of the upper stringers 2, it is necessary
to provide a second cut-away portion 48 at the end 41 of
these stringers~ The same is true also for the end 49 of the
support members 19 and 20, which must have a chamfered cut~a~ay
portion 50 so that it does not abut against the underlying
sitringers 1.
To enable the step~ to be easily moved while still
erected two small rolleri~ 51 (Figure 7) are provided at the
1~44~9
lowex ends of the upper stringers 2, so that, by slightly
raising the ~teps by the top step unit it i8 po~sible to
roli them along. -
If, in addition, it is desired to use the steps
as a bench, the tread 10 serving as a work table, it is
preferable to equip the steps with a foLding foot-rest
platform 52, on whi~h the workman can stand so as to stabilise
the steps with his weight. This platorm 52 may, for example,
be pivotally mounted by arms 53 on the transverse member 24.
In order to retain this platform when the apparatus
is in the collapsed position, it is possible to provide a .
supplementary transverse member 54 lFigure 8) between the
support members 19, 20. A hooXing strip SS attached to ~he
end of the platform 52 can then engage this transverse member
54: the transverse member 54 can also act as the stop 44.
- . When the steps are used as a bench, it is also
possible to provide, as shown in Figure 7, a tray 56 serving
for setting out tools, and mounted on the pivot axes 6 of
.the lower stringers 1, so that, like the treads 8, the tray
56 is maintained horizontal whatever the position of the
stringers 1.
~; ~ Although it is not in any way necessary to provide
~ - .
blocking for the support members 19, 20 or for the underlying
stringers 1, these being absolutely prevented from continuing
their rotation in the erected position (see circle 29), the
width of the lower horizontal part 32 of the top step unit 3
~ can also be such that, as shown in Figure 11, both the support
; - - 13 _
:'. ' ' ' ' ' ' ' ''. :: ' ' ' ' '. : ' ' , ' '
'~ . ' , : ,. ' ' :. . ', :
': . . ' .:.: . ,: , . ; ' .. ' : :
lq~ ti~3
members 19, 20 and ~lso the lower stringers 1 abut
against thc opposite ends of this horizontal part.
The invention is of course not limited to the
specific embodiments described and shown, and modiications
the
may be made. In particular,~blocking system may be altered
and accessories other than the rollers 51, ~oot-rest platform
52, and tool tray may be provided . ~ttachment means (such
as notches, screw threads or the like) may also be provided
~or one or more extension platforms, or for a vice.
Moreover, although the apparatus can be made of any
suitable material, it is preferably constructed of aluminium
sections, enabling an extremely light device to be obtained
having a very pleasing appearance. In this sense also, the
.
connecting means, as can be seen in Figure 8, are essentially
for the various points of fixing, pivots, and axes of rotation,
in the form of rivets flattened by a riveting die. In addition,
the various axes of rotation and pivoting which require the use
of washers are concealed either by the external face of the
horizontal arms 3, or by the latexal sides 15.
Of course, it will be appreciated that any other
suitable~top structure may be used in place of the arms 3,
the only requirements for such structures being that the
stringers (and if necessary, support members~ can be connected
to it with appropriate amounts of offset.
.
~ 14 -- r
